TI-99/4A Card Slot

60 PIN UNKNOWN CONNECTOR on the computer

        59     Left     1
Front ===================== Rear
        60     Right    2
Pin Name Dir Description
1 +8V --- +5V 3-T regulator voltage supply (about +8V)
2 +8V --- +5V 3-T regulator voltage supply (about +8V)
3 GND --- Ground
4 READYA   System ready (10K pull-up to +5V)
5 GND --- Ground
6 RESET* --> System reset (active low)
7 GND --- Ground
8 SCLK nc System clock (not connected)
9 LCP* nc CPU indicator 1=TI99 0=2nd generation (not connected)
10 AUDIO <-- Input audio (=AUDIOIN)
11 RDBENA* <-- Active low: enable flex cable data bus drivers (1K pull-up)
12 PCBEN H PCB enable for burn-in (always High)
13 HOLD* H Active low CPU hold request (always High)
14 IAQHA nc IAQ [or] HOLDA (logical or)
15 SENILA* H Interrupt level A sense enable (always High)
16 SENILB* H Interrupt level B sense enable (always High)
17 INTA* <-- Active low interrupt level A (=EXTINT*)
18 LOAD* nc Unmaskable interrupt (not connected)
19 D7 <-> Data bit 7 (LSB)
20 GND --- Ground
21 D5 <-> Data bit 5
22 D6 <-> Data bit 6
23 D3 <-> Data bit 3
24 D4 <-> Data bit 4
25 D1 <-> Data bit 1
26 D2 <-> Data bit 2
27 GND --- Ground
28 D0 <-> Data bit 0 (MSB)
29 A14 --> Address bit 14
30 A15 --> Address bit 15 (LSB). Also CRU output bit.
31 A12 --> Address bit 12
32 A13 --> Address bit 13
33 A10 --> Address bit 10
34 A11 --> Address bit 11
35 A8 --> Address bit 8
36 A9 --> Address bit 9
37 A6 --> Address bit 6
38 A7 --> Address bit 7
39 A4 --> Address bit 4
40 A5 --> Address bit 5
41 A2 --> Address bit 2
42 A3 --> Address bit 3
43 A0 --> Address bit 0 (MSB)
44 A1 --> Address bit 1
45 AMB H Extra address bit. Always High.
46 AMA H Extra address bit. Always High.
47 GND --- Ground
48 AMC H Extra address bit. Always High.
49 GND --- Ground
50 CLKOUT* --> Inversion of phase 3 clock (=PHI3*)
51 CRUCLK* --> Inversion of TMS9900 CRUCLOCK pin
52 DBIN --> Active high = read memory
53 GND --- Ground
54 WE* --> Write Enable (derived from TMS9900 WE* pin)
55 CRUIN <-- CRU input bit to TMS9900
56 MEMEN* --> Memory access enable (active low)
57 -12V --- -12 Volts 3-T regulator supply voltage (about -16V)
58 -12V --- -12 Volts 3-T regulator supply voltage (about -16V)
59 +12V --- +12 Volts 3-T regulator supply voltage (about +16V)
60 +12V --- +12 Volts 3-T regulator supply voltage (about +16V)

Direction is computer relative world.

Notes:

  • Signals buffered by 74LS244 in connection card: A0-A15, DBIN, MEMEN*, WE*, CLRCLK*, RESET*, CLKOUT.
  • Unbuffered signals: CRUIN, INTA*, AUDIOIN, READY
  • Data bus is buffered by two 74LS245 (one at each end of the cable),driven by RDBENA (direction set by DBIN).
  • All signals must be re-buffered on each card.
  • Always High lines (AMA, AMB, AMC, SENILA*, SENILB*, PCBEN, HOLD*) are pulled up to +5 Volts by 47 Ohms resistors.

Source: [The Hardware Book]

[Back]